The 1.6 8-valver, which measures are worthwhile?

Discussion in '8-valve' started by WAUOla, May 21, 2019.

  1. WAUOla New Member

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    Okay, I find some old threads via Google, but not when searching in here, forcing me to start a brand new thread.

    My starting point is an old 1.6 'EZ', originally supplied in my 1985 mk2. I'm interested in what you others in here give as cues for improvements, primary focus is what the Germans write as "Motorelastizität" - improved driveability for street (and potentially a one off trackday).

    • Increasing displacement/stroke:
      I plan to bolt in a 1.8 'RP' (and 4+E gearbox), seeing both 'RP' and 'EZ' are stated as having a C/R of 9.0:1, because that is what at hand from a very cost effective purchase.
    • Exhaust: Jetex 2" resonnated ordered. Is there anything to it, sourcing i.e. GTI 8V manifold and downpipe, or is it 4-1 or 4-2-1 sooner than later due cost/effect?
    • Head work:
      Seeing the 'EZ' is a 2E2 header, and the 'RP' a monojetronic (SPI), I guess both headers can be utilized for my purpose (cam will be changed). Am I right, reprofiling valves, new valve guides, bigger inlet valves and mild porting makes sense?
      (I read in here comments on 'EZ' being closer to 8.2:1, allowing for skimming 1-2mm of head deck)
    • Camshaft: for my purpose, I am considering something alike Schrick 268 or Techtonics 270 degree camshaft.
    • Carburettor: my 2E2 has actually been holding up well. Will it need any special attention, being refitted onto a 1.8L bottom-end?
     
  2. Tristan Forum Junkie

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    Is there a reason for not just fitting a gti engine?
     
  3. HPR

    HPR Administrator Admin

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    From the point of view of drivability, have good low rpm Torque and allow more breath at say 5000 upwards to have a bit more topend … a 1.8 which can be made nearer 1.9 going up in bore from 81 > to 82.5 - 83 mm
    or even fit a 2.0 unit.... but maybe thats overkill or you like things period correct or dont want to touch the bottom end ...and mainly focus on cilinderhead, inlet, exhaust and C.R


    - Headwork : This is key to get nice gains…due a better breathing engine
    light porting with focus,that inlet ports and inlet manifold line up nice to avoid mismatch
    and mainly open up the valveseats and bowl under the valve…. as here will be the largest restriction.
    On ports i would not go much bigger, just focus on nice radius transitions….
    Also rework the valves as that also brings a little extra flow


    - Compression ratio @ 9 / 1 sound a bit low to me... think around 10/ 1 , as its on a carb and its a streetcar

    - The std cam is about 258- 260 @ 0,1 mm / 220 degr @ 1.0 mm and 10.2mm valvelift ( afaik )
    with pretty low compression its key to keep duration pretty short
    so upgrade to say a 268 cam is wise … so that will be about 228 degr @ 1.0 mm and a little extra lift

    - Eventually advance the cam a couple degrees…
     
    Last edited: May 22, 2019
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  4. rubjonny

    rubjonny Administrator Admin

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    a 1.8 carb engine GU and the MK1 equivalent EX cylinder block is the same as the GTI EV, DX, 2H, PB etc and will give you the 10-1 compression. You could keep your old head or use the 1.8 carb/spi head, or even a GTI head if you like which is slightly better as standard. though if you want to keep the 2e2 carb make sure its a digifant type head then you can drill a hole for the inlet manifold coolant channel the 2e2 needs for its autochoke and waxstat to work properly. If you use the RP I'm not sure if they have the coolant channel in the inlet, or if the head can be drilled to suit the 2e2 carb though I guess it can.

    go for the GTI 4-2-1 OEM manifold and downpipe for sure, it flows better than the carb style toilet bowl. I did this on my 1.6 carb and that mod alone made it rev much more freely so I recommend it for sure.

    if you install a kjet 8v distributor this will also help as the ignition curve is that much better than the carb setup, again this mod alone on a friends 1.8 carb engine really perked it up.

    having said all the above to keep the 2e2 happy, once you start tuning the engine you may find the 2e2 cant keep up with it and tuning supplies/advice for these units are harder to come by than say the good old fashioned weber conversion which is much more widely supported. the 2e2 carb was used on 1.8 units though so you could start with 1.8 jets and see how it works for you. I guess they can be drilled out too but I havent looked into that side of things
     
  5. WAUOla New Member

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    Is simply because this is a tuck-away-car, and I like the -somewhat- idea of sticking with its origin. Going from a 1.6 to 1.8 is the same block etc, so no MOT issues to be expected. I guess I just like the idea of classic tuning, so a matter of taste. (I fully understand the argument of bang for the buck, going engine change, and IF I'd ever do that, I think it would have to be getting a 16V again and put all the badges from my old KR on.) Then again, if I need to have a serious street condender, you see, I will only step into the other classic being parked. :)

    There is also somewhat of an interest, seeing how enhancements are percieved on a 2-valver: there is also an Audi 100 10V we're considering to give a mild go, and there's also rebuilding an old Group B prototype engine (2-valve extreme).

    Thank you HPR, for a well written response!

    I do get the impression I'm not too far off with my ideas, even though I do not plan a bottom-end enhancement just yet. If so, I think doing bore and pistons for a 1.9 on a bit higher compression makes sense. But for now, please let's focus on the more basic options for bolt-ons and header tweaks; I guess good examples of the porting can be found on the sticky thread of Mr Hillclimber. Do you have any assumptions on where the driveable powerband will be on the 268 cam - if improving slightly on the lower end, and keeping breath better up until 5500-6000 area, that sounds like good option, in case a 272 gets a bit too uncivilized.

    And regarding inlet valves. Did I understand you correct, in sticking with the 38mm ones (low comb standards) as upgrading to 40mms isn't worth it in the scale of this project?
     
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  6. Jon Olds Forum Junkie

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    I run an 1600 EZ on std carb in my road CITI and realise the choke size is small so chasing high rpm gains is fairly pointless.
    Just happened to have a 2L head lying around so its cam has gone in (+1mm lift) while I replaced the hyd buckets
    Jon
     
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  7. HPR

    HPR Administrator Admin

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    Indeed , your idea on mods is inline with what i would do...to get a balanced system

    If performance is the main consideration i would go for a 272 ( or + ) cam but i had the same idea that it would/may be a bit too uncivilised…. ( altough the step is not that big )
    so opted for the 268 cam and to get an engine which has good torque low down.... and it will have enough punch to rev when asked… ( its something you need to decide what is acceptable ..)

    I dont expect that you will see the powerband shift much upwards with the 268 cam
    and as the breathing will be better with headwork, inlet and axhaust... i expect the plateau ( curve ) will lift pretty much over the full range

    On valve size, i wasnt sure it had 40 mm valves or not….
    Going from 38 to 40 mm is about 10% more valve area ( valve troath / inside seat @ 90 % of valve diameter )
    So thats a nice gain to have
    BUT considered that power output will be moderate... and its not meant to sqeeze the last drop out... then may stay with 38 mm valves


    http://www.catcams.com/engines/camshaft-setup.aspx
     
    Last edited: May 22, 2019
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  8. Jon Olds Forum Junkie

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    With HPR on valve size, stay 38mm, I've had a very well flowing head with 38mm inlets in the past
    Jon
     
  9. WAUOla New Member

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    I've been in touch with this guy before, regarding a 10V refinement (due >300 000km driven), and thought I'd check up on his work and suggestions about this idea of a build too. You can see he's work on a GTI header here: https://www.ebbt.no/vw-18-gti-toppbygg/

    A cam can be retrofitted quite easily, but doing the dirty work on a header is more ideal to priortizie now I suppose. And if the carb is getting exchanged at some point, holding back at 38mm inlets doesn't make sense, does it?
     
  10. HPR

    HPR Administrator Admin

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    Volkswagen went also bigger valves … so it wont hurt…
    Altough, a proper ported head with 38 mm valves probably flow more than a std head /mild ported head with 40 mm valves….
     
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